A possible environmental-friendly removal of Microcystis aeruginosa by using pyroligneous acid

Cyanobacteria blooms are crucial environmental issues by threatening both aquatic ecosystem and human health. A biomass by-product with antimicrobial activity, pyroligneous acid (PA) was tested for its suitability for removal of the cyanobacteria Microcystis aeruginosa (M. aeruginosa) in this work. Results show that the removal efficiency could reach up to 90% in the presence of 0.45% of PA and the inhibition to M. aeruginosa growth could extend to at least 40 days. The removal mechanism was studied. Both organic acids and phenols are functional content in M. aeruginosa removal and acetic acid is the most important one. Zeta potential analysis and morphology study show that the damage of cells dominates the flocculation and sedimentation of M. aeruginosa under low PA concentration (<0.7%), and increasing PA (≥0.7%) resulted in a trend of zeta potential to zero, thus removing any "shield" and triggering flocculation. Finally, study on the phenols residual after M. aeruginosa treatment shows that it could be close to 0 in 70 h. Therefore, this work proposes a possible method for world-wide treatment of cyanobacteria bloom and a new way for further utilization of PA.